Changing the link path doesn't of itself have any impact on formatting. If that is changing, it would be liable to do so even if the path wasn't changed - simply updating the link would do that - in which case there's a different issue to be addressed.

If the reformatting entails unwanted resizing of the linked Excel objects, this is a known issue with Word 2010 and there is registry key to fix it:
Open the Registry Editor, then navigate to:
[HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\E xcel\Options]
Add a new DWORD value:
QFE_Boston
Set the new DWORD value to 1

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]